body,a,h1，form,input,a,h2 {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    background-color: #f2f2f2;
}
.clearfix::after {
    content: "";
    display: block;
    clear: both;
    line-height: 0;
    height: 0;
    visibility: hidden;
}
input {
    border: none;
    outline: none;
}
a {
    text-decoration: none;
}
.w {
    width: 980px;
    margin: 0 auto;
    padding: 20px;
    overflow: hidden;
    box-sizing: border-box;  
    background-color: #fff;                                      
}